Fosun's offer of 69 cents per share gives Roc shareholders a 10 per cent premium to last Friday's closing share price, and a 52 per cent premium to the stock's price when the Horizon merger was announced in April.

Critics had argued the Horizon deal would have drained Roc's spare cash reserves because of Horizon's depleted balance sheet.

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Among Roc's assets are two producing oil fields in China.

Roc chairman Mike Harding said the board had unanimously concluded that Fosun's offer was superior, and a low risk route to maximise immediate value for shareholders.

Fosun's takeover needs at the acceptance of least 50.1 per cent of Roc's shareholders to proceed.

The largest shareholder, fund manager Allan Gray, has indicated it believes the takeover deal offers a fairer price, and will support the deal if there is no higher offer.

Allan Gray, which has a 20 per cent stake in Roc, opposed the Horizon merger and failed in a bid last month to force the board to hold a shareholder vote on the deal.

Horizon has conceded its deal with Roc had collapsed.

"We note and respect Roc's decision to be acquired for cash, as a low risk means of achieving immediate value for its assets," Horizon chief executive Brent Emmett said.